Broadcast Encryption Key Management via Linear Hash Chains
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Solution Overview
Problem
Current broadcast encryption methods face inefficiencies in managing user keys, particularly in reducing transmission overhead, storage overhead, and computation overhead, especially when dealing with large user groups and frequent revocations, as they often rely on tree-structure based models that require significant maintenance and are not scalable.
Innovation Solution
The method involves constructing one-way key chains using a straight line structure, where node path identifiers are assigned, and random seed value keys are generated through a hash function, allowing for efficient key distribution and revocation by defining intervals that include revoked users, thereby reducing transmission overhead and maintaining security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tree-structure based models are used for broadcast encryption, then key distribution can be achieved, but transmission overhead and storage overhead increase significantly
Solution Approach 1:
The patent segments the user set into multiple subsets and assigns different key chains to different subsets. Instead of using a single tree structure that requires comprehensive key distribution, the system divides users into groups (e.g., based on geographic location, service type, or other criteria) and assigns tailored key chains to each group. This segmentation reduces the total number of keys that need to be managed and transmitted compared to a universal tree structure.
Solution Approach 2:
The patent applies local quality by allowing different subsets of users to have different key chain configurations optimized for their specific needs. Each subset receives key chains with parameters (such as chain length, hash function selection, and update frequency) tailored to that subset's characteristics. This localized optimization reduces overall transmission overhead while maintaining security for each specific user group.
2Reliability
If tree-structure based models are used for broadcast encryption, then key distribution can be achieved, but device complexity and maintenance requirements increase
Solution Approach 1:
The patent segments the complex key management task into independent subset-managed key chains. Each subset has its own key chain that can be updated and managed independently without affecting other subsets. This segmentation eliminates the need to maintain and update a single complex tree structure, reducing device complexity and maintenance burden.
Solution Approach 2:
The patent implements dynamic key chain updates where each subset's key chain can be independently modified, extended, or revoked without reconfiguring the entire system. When users are added or removed from a subset, only that subset's key chain needs adjustment, not the entire tree structure. This dynamic flexibility significantly reduces maintenance complexity compared to static tree structures.
3Reliability
If traditional key management methods are used, then all users can be covered, but transmission overhead is proportional to the number of revoked users
Solution Approach 1:
The patent segments the user population into subsets, each with its own key chain. When revoking users, the system only needs to update the key chains of subsets containing revoked users, not all user key chains. This segmentation allows the transmission overhead to be proportional to the number of affected subsets rather than the total number of users, significantly reducing overhead in large-scale systems.
Solution Approach 2:
The patent applies partial action by updating only the necessary portions of the key management system. Instead of updating all key chains whenever any user is revoked, the system updates only the specific subset key chains that contain revoked users. This partial update approach reduces transmission overhead while maintaining complete coverage and security for all users.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces transmission overhead, storage overhead, and computation overhead while maintaining strong security, even when dealing with large user groups and frequent revocations, outperforming existing methods like the SD method by achieving transmission overhead less than the number of revoked users.
Implementation Method 1
generating key values by repeatedly applying a hash function to the assigned random seed value keys
Data Source
AI summary
A user key management method for a broadcast encryption includes assigning node path identifiers (IDs) to nodes arranged in sequence; assigning random seed value keys to the nodes according to the node path IDs; generating key values by repeatedly applying a hash function to the assigned random seed value keys; and assigning the generated key values to the nodes in sequence. Accordingly, it is possible to reduce the transmission overhead that is most important matter in the broadcast encryption to less than the number of the revoked users. Further, there is an advantage that the transmission overhead of the exemplary embodiments of the present invention is remarkably reduced compared with the Subset Difference method.